Feedback is essential to product improvement. Product releases are essential to feedback. Therefore: to improve the product you must release the product. And, the more frequent the iteration of product releases, the faster the product improves.
The product improvement process is at the heart of success. How do you determine the optimum return on investment (programmer/design time) for a list of product improvements? How do you segment the list? How much time/money do you spend on each segment? This process will take place often, so it must be systematized for optimum results.
Can you out-iterate your competitors?